Five hr after administration of bromobenzene (500 mg/kg i.p.) to rats, hepatic GSH levels are depleted by 75%. Two bromobenzene-GSH conjugates have subsequently been found in bile. Isolation and purification of these conjugates by HPLC and analysis by 13C and 1H nuclear magnetic resonance spectroscopy revealed these metabolites to be trans-3-bromo-6 (glutathion-S-y1)-cyclohexa-2,4-dien-1-01) and trans-4-bromo-6(glutathion-S-yl)-cyclo-hexa-2,4-dien-1-ol. The same two conjugates were formed in rat liver microsomes in the presence but not in the absence of 100,000 g supernatant of liver. Results with phenobarbital and 3-mehtylcholanthrene pretreated rats indicate that both conjugates are formed via the same reactive intermediate, namely bromobenzene 3,4-oxide.